I owul dlook at the lengths of times you can usually expect powewr outages in yur local area to last. Your power company can give you a rough estimate as they track allthat kind of stuff. So if the law of averages has it the power is usually off no more than an hour or two or so, go with a UPS deal or a couple of packs of batteries and a battery operated pump.........if power is known to be off for 24 or more hours, best bet is a generator set, as its not gonna take long before batteries run out or become scarce or are needed for human use as well. There is a limit on powering things up with battery power.......One thing that is easy to use and works equally well is a solar panel of correct volts in conjunction with a battery to recharge the batterys. Of course they only work during sunny days, but even in winter sun is a viable option in lots of places, even in hurricane prone areas, and its a cheap and easy way to recharge batteries instead of having to buy boxes of batteries.